1. Field of the Invention.
The present invention relates to a connector locking construction for or provided in a connector receptacle of an automotive electrical connection box and is particularly designed to improve a locking construction for fitting a connector at the end of a wiring harness into a connector receptacle of a casing made of a rigid resin such as a junction box to lock the connector and the connector receptacle.
2. Description of the Prior Art.
A prior art automotive electrical connection box, such as the junction box as shown FIGS. 4A and 4B, is constructed such that busbars 3 and insulating plates 4' are alternately placed one over another in a casing comprised of upper and lower casings 1 and 2. Tabs are formed by bending the busbars 3 to project into a receptacle 4 which is formed on the outer surface of the upper casing 1 and/or the lower casing 2 for the connection of a connector. A connector 5 connected at an end of a wiring harness W/H is fitted into the receptacle 4 of this prior art electrical connection box, and is fixed by engaging a locking portion 6 formed on the connector 5 with a lock claw 7 projecting from the inner surface of the receptacle 4.
To ensure required strength and rigidity, the upper and lower casings 1, 2 of the junction box generally are made of polypropylene added with glass and talc (PPTG). The PPTG has a disadvantage of higher brittleness as compared with polybutylene (PBT) which is used to form the connector 5 as can be seen from the following table:
______________________________________ Unit PPGT PBT ______________________________________ Tensile Elongation % 2 15 Izod Impact Strength kg cm/cm 5.0 3.0 ______________________________________
Thus, if a load is concentrated on the lock claw 7 of the receptacle 4, the lock claw 7 is likely to be cracked. Further, since the lock claw 7 of the receptacle 4 is not easily deformable, the locking operation is very difficult.
In view of the above, at the lock portions of the receptacle 4 and the connector 5, the lock claw 7 and the locking portion 6 are formed with slanted surfaces 7a, 6a on the outer surfaces of the projecting portions thereof and horizontal locking surfaces 7b, 6b are formed adjacent the slanted surfaces 7a, 6a, respectively, as shown in FIG. 4(B). The receptacle 4 and the connector 5 are locked by bringing the locking surfaces 7b, 6b into contact with each other after the slanted surfaces 7a, 6a slide in contact with each other.
However, with the above locking construction, the locking surfaces 7b, 6b are engaged after the slanted surfaces 7a, 6a are slid in contact with each other, an operator cannot easily confirm the completion of the locking operation and a locking force is weak.
In view of the above problems, an object of the present invention is to lock a receptacle and a connector in such a manner as to allow an operator to easily confirm the completion of a locking operation and to prevent damage to a lock claw of the receptacle having a higher brittleness when the connector is fitted into the receptacle of a casing e.g. made of PPGT.